Hello abifailsophiex: I'm sorry I don't know the answer to your question.

But I saw that no one has replied to your post. So I thought I would. I'm certain I've had quite a few concussions over the years.

But I'm an older person.

And for most of my life, the seriousness of concussions was not recognized. So they simply went untreated.
I've had a variety of surgeries over the years. And none of the anesthesia's I've been administered have caused me to experience what you experienced following your car accident. The only unpleasant thing I can recall following one surgery was, while I was in the hospital following surgery, I had a self-administered morphine drip for 2 or 3 days I guess it was.

Afterward, once I was back home, I had some VERY vivid dreams!

I have read that this is not unusual. This after-effect only lasted a few days though. Best wishes...